WO1994004407A1

WO1994004407A1 - Improvements in or relating to a steering wheel

Info

Publication number: WO1994004407A1
Application number: PCT/SE1993/000678
Authority: WO
Inventors: Dan Persson
Original assignee: Autoliv Development Ab
Priority date: 1992-08-17
Filing date: 1993-08-17
Publication date: 1994-03-03
Also published as: GB9217432D0; GB2269887A

Abstract

A steering wheel (1) has a rim (4) which comprises a rigid core (6) surrounded by plastic material. The plastic material surrounding the core (6) comprises an outer skin (9) and a plurality of pre-moulded elements (7, 8) located between the outer skin (9) and the core (6), the pre-moulded elements (7, 8) surrounding the core (6).

Description

"IMPROVEMENTS IN OR RELATING TO A STEERING WHEEL"

THE PRESENT INVENTION relates to a steering wheel for a motor vehicle.

A conventional steering wheel, made at the present time, consists of a metal core to which is applied a sheath or coating. Typically the coating comprises an inner layer which may be formed of ther osetting polyurethane which is moulded in position, and to which is applied a polyvinyl chloride outer coating or "skin". Frequently the polyurethane material is "foamed" and this foaming is presently accomplished utilising a blowing agent, which is typically a chlorofluorocarbon or hydrocarbon. These materials may be those sold under the Trade Mark "FREON".

The existing steering wheel presents various disadvantages. Firstly it is virtually impossible to recycle the material used in forming the steering wheel. The outer skin of PVC is of a totally different plastic than the inner layer of thermoset polyurethane, since the PVC is a thermoplastic material. Also, the thermoset polyurethane cannot be recycled. A further disadvantage, of course, is that the known procedure involves the use of chlorofluorocarbons and hydrocarbons which are known to be damaging to the environment.

Even if a steering wheel is made from plastic materials which can be recycled, the moulding of the plastic materials on to the core of the steering wheel and their subsequent removal therefrom for recycling is not always easily accomplished.

The present invention seeks to provide an improved steering wheel.

According to this invention there is provided a steering wheel having a rim which comprises a rigid core surrounded by plastic material, wherein the plastic material surrounding the core comprises an outer skin and a plurality of pre-moulded elements located between the outer skin and the core, the pre-moulded elements surrounding the core.

Preferably the pre-moulded elements are adapted to be snap-fastened to each other at spaced positions.

Conveniently the pre-moulded elements are provided, at spaced intervals, with bores extending from the exterior to the core, the material forming the outer skin passing through the bores and engaging the core to bond said pre- moulded elements to the core.

Advantageously said pre-moulded elements define at least one void.

Preferably the plastic material of the outer skin is a different plastic material to that between the skin and the metal core.

Conveniently the outer skin is formed from a thermoplastic polyurethane.

Advantageously the outer skin is approximately 3 mm thick and has 60 Shore A hardness. Preferably the pre-moulded elements which surround the core are formed of thermoplastic material.

Advantageously the pre-moulded elements between the skin and the core are formed of polypropylene.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be described, by way of example, with reference to the accompanying drawings in which

FIGURE 1 is a schematic illustration of a steering wheel in accordance with the invention,

FIGURE 2 is an enlarged sectional view taken on the line A-A of Figure 1, and

FIGURE 3 is an enlarged sectional view taken on the line B-B of Figure 1.

Referring initially to Figure 1 of the drawings, a steering wheel 1 comprises a central boss 2 from which a plurality of spokes 3 extend substantially radially, the spokes supporting an outer rim 4. At least the outer rim comprises a metal core which is provided with a covering or sheath 5 formed of a plastics material. As thus far described, the steering wheel is conventional.

Referring to Figures 2 and 3 of the drawings it can be seen that the rim of the steering wheel is formed by a metal core 6, to which the coating or sheath 5 is applied. It can be seen that the coating is formed from two separate inner elements 7,8 which co-operate to initially embrace the metal core 6 of the rim of the steering wheel and an outer covering or skin 9.

The two elements 7,8 are moulded from an appropriate thermoplastic material, such as polypropylene. The two elements 7 and 8 are, of course, moulded in moulds designed to produce elements which can be mounted on the particular metal core 6. It is to be observed that each element 7,8 is substantially semi-circular in cross-section or of "C" section, so that the two elements can be mounted on the metal rim 6 so as to completely surround the metal rim 6. At points spaced along the elements 7 and 8, co¬ operating projections 10 and recesses 11 are provided which form a snap-fit. A typical pair of projections and recesses are shown schematically in Figure 2. Corresponding projections and recesses will he provided at regular spaced intervals.

Also shown in Figure 2 are relatively large voids 12,13 defined by the elements 7 and 8. The elements 7 and 8 may define extensive voids of this type in order to minimise the amount of material actually used in making the elements 7 and 8.

Figure 3 illustrates the cross-section of the elements 7 and 8 at a position spaced from the section of Figure 2. In this region the elements 7 and 8 are each provided with a bore 14,15 which extends from the exterior of each element to the central metallic core 6.

When the two elements 7 and 8 have been mounted in position on the metal core 6, the steering wheel, with the elements 7 and 8 is located in an appropriate mould and the outer skin 9 is moulded in position, again from a thermoplastic material which may comprise thermoplastic polyurethane.

It is to be appreciated that when the outer skin 9 is moulded in position, part of the plastic material will pass down through the bores 14 and 15, thus contacting the rim 6. This will provide a positive anchoring effect ensuring that the outer sheath formed of the elements 7 and 8 cannot slide relative to the inner metal core 6. The outer skin 9 may be approximately 3 mm thick and may have a hardness of 60 Shore A. The thermoplastic polyurethane is used for the outer skin because the material is relatively soft, but is wear and heat-resistant.

When a steering wheel in accordance with the invention has finished its useful life, and is to be recycled, a knife or other cutting element may be used to cut the outer skin 9 which is then removed from the inner, pre-moulded elements 7,8. The pre-moulded elements 7,8 can then be simply removed from the core 6 by releasing the snap-fitting projections and recesses 10,11. The elements 7,8 are formed from a thermoplastics material and may therefore be recycled. The metal core may also be recycled appropriately.

Claims

CLAIMS :

1. A steering wheel(1) having a rim(4) which comprises a rigid core(6) surrounded by plastic material, characterised in that the plastic material surrounding the core(6) comprises an outer skin(9) and a plurality of pre- moulded elements(7,8) located between the outer skin(9) and the core(6) , the pre-moulded elements(7,8) surrounding the core(6) .

2. A steering wheel according to Claim 1 wherein the pre-moulded elements(7,8) are adapted to be snap-fastened to each other at spaced positions.

3. A steering wheel arrangement according to Claim 1 or 2 wherein the pre-moulded elements(7,8) are provided, at spaced intervals, with bores(14,15) extending from the exterior to the core(6), the material forming the outer skin(9) passing through the bores(14,15) and engaging the core(6) to bond said pre-moulded elements(7,8) to the core(6) .

4. A steering wheel according to any one of Claims 1 to 7 wherein said pre-moulded elements(7,8) define at least one void(12,13) .

5. A steering wheel according to any one of Claims 1 to 4 wherein the plastic material of the outer skin(9) is a different plastic material to that between the skin and the metal core.

6. A steering wheel according to any one of Claims 1 to 5 wherein the outer skin(9) is formed from a thermoplastic polyurethane.

7. A steering wheel according to Claim 6 wherein the outer skin(9) is approximately 3 mm thick and has 60 Shore A hardness.

8. A steering wheel according to any one of the preceding Claims wherein the pre-moulded elements(7,8) which surround the core(6) are formed of thermoplastic material.

9. A steering wheel according to any one of the preceding Claims wherein the pre-moulded elements(7,8) between the outer skin(9) and the core(6) are formed of polypropylene.